U.S. patent application number 13/896554 was filed with the patent office on 2013-11-21 for object determination apparatus and collision avoidance assistance apparatus.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Hiroyasu ICHIDA. Invention is credited to Hiroyasu ICHIDA.
Application Number | 20130311077 13/896554 |
Document ID | / |
Family ID | 49511167 |
Filed Date | 2013-11-21 |
United States Patent
Application |
20130311077 |
Kind Code |
A1 |
ICHIDA; Hiroyasu |
November 21, 2013 |
OBJECT DETERMINATION APPARATUS AND COLLISION AVOIDANCE ASSISTANCE
APPARATUS
Abstract
An object determination apparatus includes: a sensing device
that is mounted in a host vehicle, and that sends detection wave
and receives the detection wave reflected from an object, and that
detects the object; a detection unit that detects the state of
reflection intensity of the detection wave received by the sensing
device which changes with the distance to the object; and a
determination unit that determines that the object is a vehicle
other than the host vehicle when a peak of the reflection intensity
exceeds a predetermined threshold value. Peaks of the reflection
intensity change in accordance the distance to the object, but the
peaks regarding vehicles tend to be higher than the peaks regarding
on-road structures. Hence, by comparing a peak of the reflection
intensity with the predetermined threshold value, it can be
determined whether the detected object is a vehicle other than the
host vehicle.
Inventors: |
ICHIDA; Hiroyasu;
(Toyota-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ICHIDA; Hiroyasu |
Toyota-shi |
|
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi
JP
|
Family ID: |
49511167 |
Appl. No.: |
13/896554 |
Filed: |
May 17, 2013 |
Current U.S.
Class: |
701/301 ;
701/300 |
Current CPC
Class: |
G01S 13/931 20130101;
G01S 2013/93185 20200101; G01S 7/411 20130101; G08G 1/166 20130101;
G01S 2013/93271 20200101; B60W 30/09 20130101; G01S 2013/9318
20200101; G08G 1/165 20130101; G01S 2013/93272 20200101; G08G 1/16
20130101 |
Class at
Publication: |
701/301 ;
701/300 |
International
Class: |
G08G 1/16 20060101
G08G001/16 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2012 |
JP |
2012-114795 |
Claims
1. An object determination apparatus comprising: a sensing device
that is mounted in a host vehicle, and that sends detection wave
and receives the detection wave reflected from an object, and that
detects the object in accordance with the received detection wave;
a detection unit that detects reflection intensity of the detection
wave received by the sensing device, the reflection intensity
changing in accordance with distance to the object; and a
determination unit that determines that the object is a vehicle
other than the host vehicle when a peak of the reflection intensity
exceeds a predetermined threshold value.
2. The object determination apparatus according to claim 1, wherein
the determination unit determines whether the object is the vehicle
other than the host vehicle based on tendency of change of the
plurality of peaks of the reflection intensity detected by the
detection unit.
3. The object determination apparatus according to claim 1, wherein
the determination unit determines whether the object is the vehicle
other than the host vehicle based on magnitude of amplitude of the
reflection intensity detected by the detection unit.
4. The object determination apparatus according to claim 1, wherein
the determination unit determines that the object is an on-road
structure when it is determined that the peak of the reflection
intensity detected by the detection unit does not exceed the
predetermined threshold value.
5. A collision avoidance assistance apparatus wherein when the
object is determined as being a vehicle other than a host vehicle
by the object determination apparatus according to claim 1, a
detection region that is used for determining whether to perform a
collision avoidance control, and that is set in a traveling
direction of the host vehicle, and that is a region into which it
is determined whether the object has come is made larger than when
the object is determined as not being a vehicle other than the host
vehicle.
6. An object determination method comprising step of: sending
detection wave and receiving the detection wave reflected from an
object, and detecting the object in accordance the received
detection wave; detecting reflection intensity of the detection
wave received, the reflection intensity changing in accordance with
distance to the object; determining the object as being a vehicle
other than the host vehicle when a peak of the reflection intensity
exceeds a predetermined threshold value.
Description
INCORPORATION BY REFERENCE
[0001] The disclosure of Japanese Patent Application No.
2012-114795 filed on May 18, 2012 including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to an object determination apparatus,
a collision avoidance assistance apparatus and an object
determination method.
[0004] 2. Description of Related Art
[0005] As a related art, there is known a collision avoidance
assistance apparatus mounted in a host vehicle which detects
another vehicle or the like present in the traveling direction of
the host vehicle and which assists in avoidance of the collision
with the detected vehicle. This collision avoidance assistance
apparatus sets a detection region in the traveling direction of the
host vehicle. When an object enters the detection region, the
collision avoidance assistance apparatus performs a collision
avoidance control, for example, warning, braking and/or steering
intervention.
[0006] In the above-described collision avoidance assistance
apparatus, the collision avoidance control is sometimes
unnecessarily performed when an on-road structure that usually does
not hinder the traveling of vehicles (e.g., a guardrail, a steel
plate, etc.) enters the detection region. In order to avoid such
unnecessary activation of the collision avoidance control, it is
necessary to appropriately determine whether the object detected is
a vehicle other than the host vehicle.
[0007] On another hand, as an apparatus that determines an object
present in the traveling direction of a vehicle, there is known,
for example, an object determination apparatus described in
Japanese Patent Application Publication No. 7-244154 (JP 7-244154
A). This object determination apparatus determines whether an
object present in the traveling direction of the vehicle is a
reflector (reflecting plate) or other objects on the basis of the
reflection intensity of detection wave that is sent out from the
vehicle and reflected from the object.
[0008] However, the above-described object determination apparatus
is not capable of determining whether an object detected is a
vehicle other than the host vehicle.
SUMMARY OF THE INVENTION
[0009] The invention provides an object determination apparatus, a
collision avoidance assistance apparatus and an object
determination method that are capable of determining whether an
object detected is a vehicle other than a host vehicle.
[0010] An object determination apparatus in accordance with a first
aspect of the invention includes: a sensing device that is mounted
in a host vehicle, and that sends detection wave and receives the
detection wave reflected from an object, and that detects the
object in accordance with the received detection wave; a detection
unit that detects reflection intensity of the detection wave
received by the detection unit, the reflection intensity changing
in accordance distance to the object; and a determination unit that
determines that the object is a vehicle other than the host vehicle
when a peak of the reflection intensity exceeds a predetermined
threshold value.
[0011] In a collision avoidance assistance apparatus in accordance
with a second aspect of the invention, when an object is determined
as being a vehicle other than a host vehicle by the object
determination apparatus as described above, a detection region that
is used for determining whether to perform a collision avoidance
control, and that is set in a traveling direction of the host
vehicle, and that is a region into which it is determined whether
the object has come is made larger than when the object is
determined as not being a vehicle other than the host vehicle.
[0012] An object determination method in accordance with a third
aspect of the invention characterized by comprising steps of
sending detection wave and receiving the detection wave reflected
from an object, and detecting the object in accordance with the
received detection wave; detecting reflection intensity of the
detection wave received, the reflection intensity changing in
accordance with distance to the object; determining the object as
being a vehicle other than the host vehicle when a peak of the
reflection intensity exceeds a predetermined threshold value.
[0013] According to the aspects of the invention, it is possible to
provide an object determination apparatus, a collision avoidance
assistance apparatus and an object determination method that are
capable of determining whether an object detected is a vehicle
other than the host vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Features, advantages, and technical and industrial
significance of exemplary embodiments of the invention will be
described below with reference to the accompanying drawings, in
which like numerals denote like elements, and wherein:
[0015] FIG. 1 is a block diagram showing a construction of a
collision avoidance assistance apparatus in accordance with an
embodiment of the invention;
[0016] FIG. 2 is a flowchart showing operations of the collision
avoidance assistance apparatus shown in FIG. 1;
[0017] FIG. 3 is a diagram showing peaks of the reflection
intensity in comparison among vehicles other than a host vehicle
and on-road structures;
[0018] FIGS. 4A to 4C are diagrams showing operations performed
when an object detected is determined as being a vehicle other than
the host vehicle;
[0019] FIGS. 5A to 5C are diagrams showing operations performed
when an object detected is determined as being an on-road
structure;
[0020] FIG. 6 is a diagram showing a tendency of change of peaks of
the reflection intensity in comparison between vehicles other than
the host vehicle and on-road structures; and
[0021] FIGS. 7A and 7B are diagrams showing the magnitudes of
amplitudes of the reflection intensity between a vehicle other than
the host vehicle and an on-road structure.
DETAILED DESCRIPTION OF EMBODIMENTS
[0022] Embodiments of the invention will be described in detail
below with reference to the accompanying drawings. Note that the
same elements are denoted by the same reference characters in the
drawings, and redundant descriptions are omitted below.
[0023] Firstly, with reference to FIG. 1, a construction of a
collision avoidance assistance apparatus in accordance with an
embodiment of the invention will be described. FIG. 1 is a block
diagram showing a construction of the collision avoidance
assistance apparatus in accordance with an embodiment of the
invention.
[0024] The collision avoidance assistance apparatus is an apparatus
that assists in avoidance of a collision with a vehicle other than
a host vehicle, on the basis of a result of detection of an object.
As shown in FIG. 1, the collision avoidance assistance apparatus
mounted in a vehicle (not shown) includes a detection sensor 10
(sensing device 10), an ECU (Electronic Control Unit) 20 and an
assistance device 30. The ECU 20 is connected to the detection
sensor 10. The assistance device 30 is connected to the ECU 20.
[0025] The detection sensor 10 functions as a sensing device that
is configured to send detection wave, receive detection wave
reflected from an object and thus detect the object. The detection
sensor 10 is assumed to be installed on a front surface of the
vehicle in this embodiment, but may also be installed on a rear
surface of the vehicle. Furthermore, as the detection sensor 10, a
millimeter wave radar sensor is employed in this embodiment, but a
laser radar sensor or the like may also be employed.
[0026] The detection sensor 10 detects an object by sending
detection wave forward from the vehicle and receiving detection
wave reflected from an object present in front of the vehicle.
Then, the detection sensor 10 supplies a detection result to the
ECU 20. The detection result includes the reflection intensity of
the detection wave reflected from the object, distance information
indicating the distance to the object, lateral position information
indicating a lateral positional relationship with the object, and
velocity information indicating the relative velocity of the
object. Incidentally, the reflection intensity of detection wave is
the reception intensity of detection wave that is reflected from an
object and received by the detection sensor 10.
[0027] The ECU 20 includes a storage unit 21, a detection unit 22,
a determination unit 23, a setting unit 24 and a control unit 25.
It is to be noted herein that the storage unit 21, the detection
unit 22 and the determination unit 23, together with the detection
sensor 10, constitute an object determination apparatus that
determines whether an object is a vehicle other than the host
vehicle, on the basis of a result of detection regarding the
object.
[0028] The ECU 20 is made up mainly of a CPU (Central Processing
Unit) a ROM (Read-Only Memory) and a RAM (Random Access Memory).
The CPU realizes the functions of the storage unit 21, the
detection unit 22, the determination unit 23, the setting unit 24
and the control unit 25 by reading out programs from the ROM and
the like and executing them on the RAM. Incidentally, the functions
of the storage unit 21, the detection unit 22, the determination
unit 23, the setting unit 24 and the control unit 25 may also be
realized by two or more ECUs.
[0029] The storage unit 21 temporarily stores detection results
supplied from the detection sensor 10. As the storage unit 21, a
storage element, such as a memory or the like, is employed. The
detection results stored in the storage unit 21 are read out
according to need. Detection results are read out for the purpose
of the processing performed in the detection unit 22, the
determination unit 23 or the control unit 25.
[0030] The detection unit 22 detects the state of the reflection
intensity of detection wave received. The detection unit 22 detects
the state of the reflection intensity of the detection wave
supplied from the detection sensor 10, and supplies a result of
detection result to the determination unit 23. The detection unit
22 detects a peak of the reflection intensity on the basis of the
state of the reflection intensity. A peak of the reflection
intensity refers to a convex point that appears on a detection
waveform that shows a relationship between the distance (relative
distance) to the object and the reflection intensity.
[0031] Furthermore, the detection unit 22 may detect the tendency
of change of peaks of the reflection intensity and/or the magnitude
of amplitude of the reflection intensity. The tendency of change of
peaks refers to the tendency of distribution of peaks over the
detection waveform (the tendency of increase and/or decrease in
intensity of a plurality of peaks). The magnitude of amplitude
refers to the width of up-down fluctuations (the magnitude of
fluctuations) of the detection waveform. Incidentally, the
detection unit 22 detects the tendency of change of peaks, the
magnitude of amplitude, etc., on the basis of the state of the
reflection intensity.
[0032] The determination unit 23 determines the kind of an object
on the basis of the state of the reflection intensity. The
determination unit 23 determines the kind of the object on the
basis of distance information, the lateral position information,
the velocity information, and the state of the reflection intensity
supplied from the detection unit 22. The determination unit 23
supplies the kind of an object to a setting unit 24. The distance
information, the lateral position information and the velocity
information are supplied from the detection sensor 10. In this
embodiment, results of the determination are used for the setting
of a detection region for the collision avoidance control, but may
also be used for other uses.
[0033] The determination unit 23 determines that the object is a
vehicle other than the host vehicle, when a peak of the reflection
intensity exceeds a predetermined threshold value. Peaks of the
reflection intensity change according to the distance to the
object. It is to be noted herein that the predetermined threshold
value is a threshold value for use for determining the kind of the
object. In particular, the predetermined threshold value is a
threshold value for use for determining whether the detected object
is a vehicle other than the host vehicle or an on-roach structure.
The predetermined threshold value is set beforehand according to
the distance to an object so that a vehicle other than the host
vehicle and an on-road structure can be discriminated from each
other. The on-road structure is an object that does not hinder the
normal traveling of a vehicle. For example, the on-road structure
is a guardrail, a steel plate (e.g., a manhole lid, a ditch cover,
etc.)
[0034] When a peak of the reflection intensity of the detection
wave reflected from a detected object exceeds the predetermined
threshold value, it is determined that this object is a vehicle
other than the host vehicle. Peaks of the reflection intensity
change with the distance to the object. However, peaks of the
reflection intensity of a vehicle other than the host vehicle tend
to be higher than peaks of the reflection intensity of an on-road
structure. Hence, by comparing the peak of the reflection intensity
with the predetermined threshold value, it can be accurately
determined whether the detected object is a vehicle other than the
host vehicle.
[0035] Furthermore, the determination unit 23 may determine whether
an object is a vehicle other than the host vehicle on the basis of
the tendency of change of a peak of the reflection intensity that
changes according to the distance to the object. The peak of the
reflection intensity changes with the distance to the object as
stated above. Due to the reflection characteristics of the object,
the peak of the reflection intensity of a vehicle other than the
host vehicle increases as the host vehicle approaches the vehicle.
On the other hand, the peak of the reflection intensity of an
on-road structure tends to decrease as the host vehicle approaches
the on-road structure in the case where the posture of the host
vehicle has changed due to steering avoidance. Hence, it can be
more accurately determined whether the object is a vehicle other
than the host vehicle on the basis of the tendency of change of the
peak of the reflection intensity.
[0036] Furthermore, the determination unit 23 may determine whether
the object is a vehicle other than the host vehicle on the basis of
the magnitude of amplitude of the reflection intensity, which
changes according to the distance to the object. Although the
amplitude of the reflection intensity changes with the distance to
the object, the amplitude of the reflection intensity of a vehicle
other than the host vehicle tends to more greatly change than the
amplitude of the reflection intensity of an on-road structure, due
to the reflection characteristics of objects. Hence, it can be more
accurately determined whether the object is a vehicle other than
the host vehicle on the magnitude of amplitude of the reflection
intensity.
[0037] The setting unit 24 sets a detection region in the traveling
direction of the host vehicle on the basis of a result of the
determination regarding an object. The setting unit 24 sets a
detection region in the traveling direction of the vehicle on the
basis of the result of the determination supplied from the
determination unit 23. It is to be noted herein that the detection
region refers to a region that is virtually set in order to
determine whether to perform the collision avoidance control. The
detection region is set in the traveling direction of the vehicle.
The detection region is a region whose shape is rectangular,
semielliptical, etc. The detection region is usually set as an
ordinary region that extends several meters in the traveling
direction of the vehicle. The ordinary region extends several
meters in the traveling direction of the vehicle. The detection
region is set as an enlarged region than ordinary region when a
detected object is determined as being a vehicle other than the
host vehicle. The enlarged region is a region that is temporarily
expanded in the traveling direction of the vehicle.
[0038] Then, in the collision avoidance assistance apparatus, the
collision avoidance control is executed when it is determined that
an object has entered the detection region. That is, when it is
determined that an object is a vehicle other than the host vehicle,
the detection region of the detection sensor is made larger than
when it is determined that the object is not a vehicle other than
the host vehicle. The detection region of the detection sensor is
used for determining whether to perform the collision avoidance
control, and that is set in the traveling direction of the host
vehicle, and that is a region into which it is determined whether
an object has come. Thus, the use of an expanded detection region
makes it possible to perform the collision avoidance control with
an enough time margin prior to the collision with the vehicle other
than the host vehicle.
[0039] The control unit 25 controls the assistance in avoiding a
collision with a vehicle other than the host vehicle on the basis
of a result of the determination regarding the object present in
the detection region. The control unit 25 determines whether an
object has come into the detection region. The control unit 25
determines whether an object has entered the detection region on
the basis of a detection result (distance information, lateral
position information) and the set range of the detection region.
The detection result is supplied from the detection sensor 10. The
set range of the detection region is set by the setting unit
24.
[0040] Then, the control unit 25, when determining that an object
has entered the detection region, then controls the assistance
device 30 according to the position of the object that has entered
the detection region and/or the state of movement thereof. For
example, when a predicted time point of collision with the object
which is found according to the position and/or the state of
movement of the object exceeds a predetermined threshold value, the
control unit 25 only activates a warning operation, and when the
predicted time point of collision is less than the threshold value,
the control unit 25 activates control intervention as well as the
warning.
[0041] The assistance device 30 executes collision avoidance
assistance, such as warning, braking and/or steering intervention,
etc., under the control by the control unit 25. The assistance
portion 30, with regard to entrance of an object into the detection
region, gives warning by using information perceptible to a driver,
such as visual information, auditory information, etc. Furthermore,
the assistance device 30 intervenes with the steering or braking
control so as to assist in the avoidance of a collision with an
object that has entered the detection region.
[0042] Next, operations of the collision avoidance assistance
apparatus in accordance with the embodiment of the invention will
be described.
[0043] FIG. 2 is a flowchart showing operations of the collision
avoidance assistance apparatus shown in FIG. 1. The collision
avoidance assistance apparatus repeatedly executes a process shown
in FIG. 2 at every predetermined time period.
[0044] As shown in FIG. 2, the detection sensor 10 detects an
object on the basis of a result of reception of the detection wave
reflected from the object (S11). At this stage, the presence and
the position of the object are determined, but the kind of the
object is not determined yet.
[0045] The detection unit 22 detects the state of the reflection
intensity of the detection wave on the basis of a result of
detection of the object (S12). The reflection intensity of the
detection wave changes with the distance to the object.
[0046] FIG. 3 is a diagram showing peaks of reflection intensity in
comparison between vehicles other than the host vehicle and on-road
structures. In FIG. 3 there are shown detection waveforms each of
which shows a relationship between the distance (relative distance)
to a corresponding object and the reflection intensity of the
detection wave reflected from the object. FIG. 3 shows examples of
detection waveforms regarding three kinds of vehicles other than
the host vehicle (preceding vehicles) that are traveling at low
speed as well as on-road structures (a guardrail and a steel
plate).
[0047] As shown in FIG. 3, although peaks of the reflection
intensity change with the distance between the host vehicle and the
object, peaks of the reflection intensity of vehicles other than
the host vehicle tend to be higher than peaks of the reflection
intensity of on-road structures. Hence, by comparing peaks of
reflection intensity with a predetermined threshold value TH, it
can be determined whether an object detected is a vehicle other
than the host vehicle.
[0048] It is to be noted herein that the predetermined threshold
value TH is set according to the relative distance to the object so
that a vehicle other than the host vehicle and an on-road structure
can be discriminated from each other. In the example shown in FIG.
3, the predetermined threshold value TH is defined by a straight
line that monotonously rises with decreases in the relative
distance. However, the predetermined threshold value TH may also be
defined by a combination of straight lines, a combination of
curves, or a combination of straight and curved lines.
[0049] Referring back to FIG. 2, after the state of the reflection
intensity of the detection wave is detected in S12, the
determination unit 23 determines whether a peak of the reflection
intensity exceeds the predetermined threshold value (S13). This
peak determination is performed by comparing the peak of the
reflection intensity and the predetermined threshold value that
corresponds to the relative distance of the object measured at the
time of occurrence of the peak.
[0050] It is to be noted herein that in order to secure a
sufficient determination accuracy, the peak determination is
performed if the relative distance satisfies a predetermined
condition (the relative distance is not too long and not too short.
e.g., the relative distance be within a distance range R shown in
FIG. 3) and the lateral position of the object satisfies a
predetermined condition (the object be substantially directly
facing the front of the host vehicle).
[0051] Furthermore, the peak determination may be performed with
respect to one peak of the detection waveform, and may also be
performed with respect to a plurality of peaks. The peak
determination can be performed with respect to more peaks that
occur within a period during which the relative distance of the
object satisfies the predetermined condition, as the relative
velocity of the object is smaller. By synthetically considering
results of the determination with respect to a plurality of peaks,
the determination accuracy can be improved.
[0052] The determination unit 23 determines whether the object is a
vehicle other than the host vehicle on the basis of the result of
the determination provided in S13. FIG. 2 illustrates a case where
the kind, of the object is determined on the basis of comparison of
a peak of the reflection intensity with the predetermined threshold
value. Furthermore, the kind of the object may be determined by
taking into account the tendency of change of peaks of the
reflection intensity or the magnitude of amplitude of the
reflection intensity.
[0053] Then, when in S13 it is determined that a peak of the
reflection intensity exceeds the predetermined threshold value, it
is determined that the object is a vehicle other than the host
vehicle (S14). In that case, the setting unit 24 sets the detection
region as an expanded region that is temporarily expanded
(S15).
[0054] On the other hand, when in S13 it is determined that a peak
of the reflection intensity does not exceeds the predetermined
threshold value, it is determined that the object is an on-road
structure (S16). In that case, the setting unit 24 sets the
detection region as an ordinary region described below (S17).
[0055] After the detection region is set in S15 or S17, the control
unit 25 determines whether the object is within the detection
region (S18). Then, when it is determined that the object has
entered the detection region, the control unit 25 activates the
warning or the control intervention of the assistance device 30
(S19). Incidentally, when in S18 it is determined that the object
has not entered the detection region, the process ends.
[0056] FIGS. 4A to 4C are diagrams showing operations performed
when a detected object T is a vehicle O1 other than the host
vehicle. As shown in FIG. 4A, during a state in which the detection
region is set as an ordinary region An, the determination unit 23
determines whether the object T present forward of the vehicle C
(host vehicle) is a vehicle O1 other than the host vehicle. Then,
as shown in FIG. 4B, the setting unit 24 sets an expanded region Ae
that is temporarily expanded, as the detection region. Then, as
shown in FIG. 4C, when the object T enters the expanded region Ae
as the vehicle C moves along a traveling path D, the control unit
25 activates the assistance device 30. Therefore, when the expanded
region Ae is used, the collision avoidance control can be performed
with time margin prior to a collision with the object T.
[0057] FIGS. 5A to 5C are diagrams showing operations performed
when a detected object T is determined as an on-road structure O2.
As shown in FIG. 5A, during a state in which an ordinary region An
is set as the detection region, the determination unit 23
determines that an object T present forward of the vehicle C (host
vehicle) is an on-road structure O2 (a guardrail in an example
shown in FIGS. 5A to 5C). Then, the setting unit 24 maintains the
setting of the ordinary region An as the detection region as shown
in FIG. 5B. Then, as shown in FIG. 5C, while the vehicle C moves
along a traveling path D, the control unit 25 does not activate the
assistance device 30 as long as the object T does not enter the
detection region (ordinary region An).
[0058] FIGS. 5B to 5C also show, as a comparative example, a case
where an expanded region Ae is set for detection of the object T
present forward of the vehicle C, regardless of the kind of the
object T. In this case, when the on-road structure O2 is detected,
the expanded region Ae is set as the detection region as shown by a
broken line in FIG. 5B. Then, if the object T enters the detection
region (expanded region Ae) as the vehicle C moves along the
traveling path D, the assistance device 30 is activated.
[0059] Consequently, in the case where a guardrail (an on-road
structure) is present, although the on-road structure can be
avoided by normally performing the steering along the traveling
path D, the collision avoidance control is activated. Incidentally,
in the case where a steel plate is present, although the steel
plate can be avoided by normal steering or although there is no
need to take an avoiding action, the collision avoidance control is
activated. Hence, it sometimes happens that the driver is disturbed
by unnecessary warning or unnecessary control intervention.
[0060] In the flowchart shown in FIG. 2, illustration is made in
conjunction with the case where the kind of a detected object is
determined on the basis of a result of the comparison of a peak of
the reflection intensity with the predetermined threshold value.
However, the kind of the object may also be determined by taking
into account the tendency of change of peaks of the reflection
intensity or the magnitude of amplitude thereof.
[0061] FIG. 6 is a diagram showing the tendencies of change of
peaks of the reflection intensity between vehicles other than the
host vehicle and on-road structures. FIG. 6 shows, together with
the detection waveforms shown in FIG. 3, examples of a tendency of
change Tr1 of peaks of the reflection intensity of a vehicle other
than the host vehicle (an average tendency of change regarding
three kinds of vehicles other than the host vehicle) and a tendency
of change Tr2 of peaks of the reflection intensity of an on-road
structure (an average tendency of change of regarding two kinds of
on-road structures) in comparison.
[0062] As shown in FIG. 6, although peaks of the reflection
intensity change with the distance to the object, peaks of the
reflection intensity of a vehicle other than the host vehicle
increases as the host vehicle approaches the vehicle, due to the
reflection characteristics of the object (vehicle). On the other
hand, peaks of the reflection intensity of an on-road structure
tends to decrease as the host vehicle approaches the on-road
structure in the case where the vehicle posture changes due to
steering avoidance. This is because the detection wave reflected
from the on-road structure becomes less as the host vehicle
approaches the on-road structure, in association with the position
of the host vehicle (detection sensor 10) relative to the on-road
structure. Hence, on the basis of the tendency of change of peaks
of the reflection intensity, it can be more accurately determined
whether the object is a vehicle other than the host vehicle.
[0063] The determination based on the tendency of change of peaks
is performed by, for example, determining whether the tendency of
change of peaks of the reflection intensity switches from an
increase tendency to a decrease tendency as the relative distance
to the object passes a predetermined relative distance. The
predetermined relative distance is set beforehand so that a vehicle
other than the host vehicle and an on-road structure can be
discriminated from each other. A result of the determination may be
used for the setting of the detection region for the collision
avoidance control, and may also be used for other uses.
[0064] Furthermore, the determination based on the tendency of
change of peaks may be performed singularly, or may also be
performed in combination with the determination based on comparison
of the peaks with the predetermined threshold value. That is, when
peaks do not decrease in intensity as the host vehicle approaches
the object or when peaks exceed the predetermined threshold value,
it may be determined that the object is a vehicle other than the
host vehicle. It may be determined that the object is a vehicle
other than the host vehicle, when peaks do not decrease in
intensity as the host vehicle approaches the object and peaks
exceed the predetermined threshold value.
[0065] FIGS. 7A and 7B are diagrams showing the magnitudes of
amplitude of the reflection intensity of a vehicle other than the
host vehicle and an on-road structure in comparison. FIGS. 7A show
an example of the magnitude of amplitude of the reflection
intensity of a vehicle other than the host vehicle and FIGS. 7B
shows an example of the magnitude of amplitude of the reflection
intensity of an on-road structure.
[0066] As shown in FIGS. 7A and 7B, although the amplitude of the
reflection intensity changes with the distance to the object, the
amplitude of the reflection intensity of a vehicle other than the
host vehicle (indicated by vertical arrows in FIG. 7A) tends to be
larger than the amplitude of the reflection intensity of an on-road
structure (indicated by vertical arrows in FIG. 7B), due to the
reflection characteristics of the objects. This is because, in
association with the positional relationship between the host
vehicle (the detection sensor 10) and a vehicle other than the host
vehicle, the detection wave reflected from a vehicle other than the
host vehicle is more subject to the influence of phase interference
of a multipath system than the detection wave reflected from an
on-road structure is. Hence, it can be more accurately determined
whether the object is a vehicle other than the host vehicle, on the
basis of the magnitude of amplitude of the reflection
intensity.
[0067] It is to be noted herein that the determination based on the
magnitude of amplitude is performed by, for example, determining
whether the amplitude of the reflection intensity exceeds a
predetermined threshold value. The predetermined threshold value is
set beforehand so that vehicles other than the host vehicle can be
discriminated from on-road structures. Results of the determination
may be used for the setting of a detection region for the collision
avoidance control, and may also be used for other uses.
[0068] Furthermore, the determination based on the magnitude of
amplitude is performed in combination with the determination based
on comparison of a peak with the predetermined threshold value.
That is, when a peak exceeds the predetermined threshold value and
the amplitude is large, it is determined that the object is a
vehicle other than the host vehicle. Alternatively, the
determination based on the magnitude of amplitude may be performed
in combination with the determination based on the tendency of
change of peaks. Further alternatively, the determination based on
the magnitude of amplitude may also be performed in combination
with both the determination based on comparison of a peak with the
predetermined threshold value and the determination based on the
tendency of change of peaks.
[0069] As described above, according to the object determination
apparatus in accordance with the embodiment of the invention, when
a peak of the reflection intensity of the detection wave reflected
from an object detected exceeds the predetermined threshold value,
it is determined that the object is a vehicle other than the host
vehicle. Although peaks of the reflection intensity change with the
distance to the object, peaks of the reflection intensity of a
vehicle other than the host vehicle tends to be higher than peaks
of the reflection intensity of an on-road structure (a guardrail, a
steel plate, etc.). Hence, by comparing peaks of the reflection
intensity with the predetermined threshold value, it can be
determined whether the detected object is a vehicle other than the
host vehicle. It can be accurately determined whether the detected
object is a vehicle other than the host vehicle.
[0070] Furthermore, the determination unit 23 may determine whether
the object is a vehicle other than the host vehicle on the basis of
the tendency of change of peaks of the reflection intensity which
change with the distance to the object. It is to be noted herein
that although peaks of the reflection intensity change with the
distance to the object, peaks of the reflection intensity of a
vehicle other than the host vehicle increase in intensity as the
host vehicle approaches the vehicle, due to the reflection
characteristics of the object. On the other hand, peaks of the
reflection intensity of an on-road structure tend to decrease in
intensity as the host vehicle approaches the on-road structure when
the posture of the host vehicle changes due to steering avoidance.
Hence, on the basis of the tendency of change of peaks of the
reflection intensity, it can be more accurately determined whether
the object is a vehicle other than the host vehicle.
[0071] Furthermore, the determination unit 23 may also determine
whether the object is a vehicle other than the host vehicle on the
basis of the magnitude of amplitude of the reflection intensity
which changes with the distance to the object. It is to be noted
herein that although the amplitude of the reflection intensity
changes with the distance to the object, the amplitude of the
reflection intensity of a vehicle other than the host vehicle tends
to more greatly change than the amplitude of the reflection
intensity of an on-road structure, due to the reflection
characteristics of the objects. Hence, on the basis of the
magnitude of amplitude of the reflection intensity, it can be more
accurately determined whether the object is a vehicle other than
the host vehicle.
[0072] Furthermore, according to the collision avoidance assistance
apparatus in accordance with the embodiment of the invention, the
use of an expanded detection region makes it possible to perform
the collision avoidance control with time margin prior to the
collision with a vehicle other than the host vehicle.
[0073] Furthermore, it is to be noted that the foregoing embodiment
merely illustrates a best mode for carrying out the object
determination apparatus and the collision avoidance assistance
apparatus of the invention and that the object determination
apparatus and the collision avoidance assistance apparatus of the
invention are not limited to those described above in conjunction
with the embodiment. The object determination apparatus and the
collision avoidance assistance apparatus of the invention may be
those obtained by modifying the object determination apparatus and
the collision avoidance assistance apparatus in accordance with the
foregoing embodiment or by applying them to other apparatuses,
without departing from the gist of the invention.
[0074] Furthermore, the invention is also applicable to programs
for determining that an object detected is a vehicle other than the
host vehicle when a peak of the reflection intensity of the
detection wave reflected from the object exceeds the predetermined
threshold value according to the above-described method, or to
computer-readable recording media that store such programs. The
invention is also applicable to programs for expanding the
detection region when the object is determined as being a vehicle
other than the host vehicle according to the above-described
method, or to computer-readable recording media that store such
programs.
[0075] Furthermore, the foregoing embodiment is described above in
conjunction with the case where a part of the functions of the
object determination apparatus and a part of the functions of the
collision avoidance assistance apparatus are realized by the single
ECU 20. However, these functions may also be realized by a
plurality of ECUs instead of the single ECU 20.
[0076] While the disclosure has been explained in conjunction with
the specific exemplary embodiments thereof, it is evident that many
alternatives, modifications, and variations will be apparent to
those skilled in the art. Accordingly, the exemplary embodiments of
the disclosure as set forth herein are intended to be illustrative,
not limiting. There are changes that may be made without departing
from the scope of the disclosure.
* * * * *